
#extension GL_ARB_texture_rectangle : enable
uniform sampler2DRect arrayA;
uniform sampler2DRect arrayB;

void main(void) {
   
   vec2 pcoo = gl_FragCoord.xy;
   float a = texture2DRect(arrayA, pcoo).r;
   float b = texture2DRect(arrayB, pcoo).r;
   gl_FragColor.r = a + b;
}
